1. Field of the Invention
The present invention relates to a satellite broadcast receiving apparatus capable of commonly utilizing a single antenna by a plurality of receiving systems.
2. Description of the Prior Art
In such a conventional satellite broadcast receiving apparatus, a frequency of a reception signal is down-converted with employment of a down-converter installed just under an antenna, and a down-converted signal is conducted via a coaxial cable to a tuner for receiving a satellite broadcasting signal, which is installed within a room.
At this time, the conventional satellite broadcast receiving apparatus can supply power from a power source to the down-converter via the coaxial cable for the antenna output signal, so that the antenna can be installed with a simple wiring operation.
In an apartment such as a Penthouse, such a system has been established that power of a power source exclusively installed is supplied via a coaxial cable to a down-converter, and an output signal derived from the down-converter, which is transferred via this coaxial cable, is distributed to the respective homes or apartments (this will be referred to a "co-distributing system").
When the satellite broadcast receiving apparatuses are connected to such a co-distributing system, in the satellite broadcast receiving apparatus installed in the respective homes, if the power from the power source is supplied to the coaxial cable in a similar manner to the usual receiving system, then both of the power from the power source exclusively used to the co-distributing system and the power from the power source employed in this satellite broadcast receiving apparatus are supplied to the down-converter at the same time.
In this case, there is a risk that the down-converter connected to this coaxial cable may malfunction in the co-distributing system. In the worst case, the down-converter may catch fire.
As a consequence, in case of such a malfunction, the power supply control must be carried out with respect to the coaxial cables in the home-use satellite broadcast receiving apparatus.
In other words, the operation button for setting interruption of the power supply is provided in the conventional satellite broadcast receiving apparatus. The supply of the power derived from the power source of the satellite broadcast receiving apparatus is stopped by manipulating this operation button.
To the contrary, in the home use system similar to such a co-distributing system, there is a possibility that a down-converter is commonly utilized in a plurality of satellite broadcast receiving apparatuses. In this case, it is required to supply power from any one of these satellite broadcast apparatus to the down-converter, instead of the power source exclusively used for the co-distributing system. However, when the main power source is turned OFF in the conventional satellite broadcast receiving apparatus, the DC power supply to the down-converter is interrupted. As a result, if one satellite broadcast receiving apparatus is allocated to supply the power to the down-converter, when the main power supply of this satellite broadcast receiving apparatus is set to the OFF state, no satellite broadcasting program can be received by the remaining satellite broadcast receiving apparatuses.
Also, even when such one satellite broadcast receiving apparatus is allocated to supply the power to the down-converter, there is a risk that a user mistakenly operates this receiving apparatus. Accordingly, there is another problem that such a failure cannot be completely prevented.